Plastic is surprising porous and absorbs color from liquids very easily. Once it is absorbed, it is not coming back out. Plastic bottles of swimming pool acid will emit a very slight acidic fume over time. Place a gallon near steel parts and you will see within a few months that the steel will have starting rusting. Highly evaporative solvents will also creep very slowly through plastic bottles. That is why most come is steel containers, not plastic.